The present invention relates to a hinge used by being mounted on an opening and closing connection, such as a door, and a method of producing the same, and more particularly it relates to a hinge with no tubular portion for receiving a shaft bar, and a method of producing the same.
A conventional hinge used by being mounted on an opening and closing section, such as a door, comprises two flap plates curled at one of their respective lateral ends to form tubular portions, a shaft bar inserted in the two tubular portions to hold them for turning movement thereon, legs force-fitted into the open ends of the two tubular portions to prevent the shaft bar from falling off, and a flat head knob fixed in position. In some hinges, a ring made of a synthetic resin, such as nylon, which ensures smooth slide movement and little wear is externally fitted between the two tubular portions.
In this type of hinges, since the two flap plates are formed at one of their respective lateral ends with tubular portions, the number of steps for producing the two flap plates is correspondingly increased and hence the processing cost is high. Particularly in a large-sized hinge, the material for flap plates has an increased thickness and hence is harder to process and takes a longer processing time, resulting in a high cost. Further, there is a drawback that during a long time of use of the hinge, the flat head knob can wear out to cause the shaft bar to slip off, leading to damage to the hinge and door. In some types, to prevent the shaft bar from slipping off, the flat head knob is welded to the tubular portion or otherwise fixed by inserting a pin therein laterally of the tubular portion, but these types are hard to produce, leading to an increase in cost.
The present invention, which has been accomplished in view of these problems in the prior art, has for its object the provision of a hinge of epoch-making construction wherein contrary to the conventional technical concept there is no curled tubular portion and hence no shaft bar is used.
Another object of the present invention is to provide a method of producing the aforesaid hinge.
A hinge according to the present invention comprises a left-hand side flap plate having on its right-hand end at least one shaft plate having at least one communication hole and at least one semicircular locking hole, a right-hand side flap plate having on its left-hand end at least one shaft plate having at least one communication hole and at least one semicircular locking hole, said semicircular locking holes coming in contact with each other to form a circular portion when the shaft plates of said left-hand and right-hand side flap plates are fitted together, a ball fitted in said circular portion and having a washer fitted thereon, and core shafts communicating with the opposite surfaces of the shaft plates through said communication holes and separated from each other by said washer.
Further, a method of producing the hinge according to the invention comprises the steps of fabricating a left-hand side flap plate having on its right-hand end at least one shaft plate having at least one communication hole and at least one semicircular locking hole and a right-hand side flap plate having on its left-hand end at least shaft plate having at least one communication hole and at least one semicircular locking hole, fitting the shaft plates of said left-hand and right-hand side flap plates together to thereby cause said semicircular locking holes to form a circular portion, fitting in said circular portion a ball having a washer fitted thereon, and forming core shafts communicating with the opposite surfaces of the shaft plates through said communication holes.
The core shafts are preferably formed by injection molding a synthetic resin, such as polyamide, polyacetal or polyester or by casting a die casting alloy, such as an aluminum alloy or zinc alloy.
Further, the shaft plate portions extend preferably in uneven parallel relation to the flap plates.
Since the hinge according to the invention uses no flap plate having a tubular portion as in the conventional hinge, the right and left flap plates are very easy to fabricate and the number of processing steps is correspondingly reduced. Further, since there is no need for the difficult operation of fixing a head knob at the open end of the tubular portion to prevent the shaft bar from slipping off as in the conventional hinge, the assembly operation is very easy.
Further, since the hinge according to the invention turns through the washer mounted on the ball, the opening and closing operation thereof is very smooth, and since the load is imposed on the washer through the core shafts, there is no danger of producing localized load.
The invention will be described in more detail with reference to the accompanying drawings showing an embodiment thereof.